1.1 Introduction to the report

Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC) is Australia's first nationally representative longitudinal study of child development. The purpose of the study is to provide data that enable a comprehensive understanding of development and life-course trajectories within Australia's current social, economic and cultural environment. The longitudinal nature of the study enables researchers to examine the dynamics of change through the life course as children develop, and to go beyond the static pictures provided by cross-sectional statistics. The study thereby gives policy-makers and researchers access to quality data about children's development in the contemporary Australian environment.

The study was initiated and is funded by the Australian Government Department of Social Services (DSS), and is conducted in partnership with the Australian Institute of Family Studies (AIFS) and the Australian Bureau of Statistics (ABS). A consortium of leading researchers and experts from universities and research agencies provide advice to the study.

The purpose of the LSAC Annual Statistical Report series is to provide a snapshot of some of the data from the study and to address policy-relevant questions about aspects of Australian children's lives and development. The reports make use of the longitudinal nature of LSAC data to describe the dynamics of change as children develop, and how their families and lives change as they grow older. Previous volumes have covered a wide range of topics, including children's screen time, the body image of primary school children, children's primary school attendance, access to preschool education and parenting practices. A full list of topics covered by past volumes is given at the end of the report.

This is the seventh volume in the LSAC Annual Statistical Report series. There are now six waves of LSAC data, with the older children in LSAC aged 14-15 years at the sixth wave. Many of the chapters presented in this report focus on the circumstances of these older children: chapters 3 and 2 look at employment experiences and career aspirations, chapter 6 examines deliberate self-harm, chapter 4 looks at alcohol use and chapter 5 focuses on young carers. Other chapters make use of the longitudinal data to examine changes in children's family circumstances across waves: chapter 8 analyses how families vary according to the age of mothers when first children were born, and chapter 7 examines teaching practices in primary schools.

The remaining subsections, below, provide a brief overview of LSAC and present information about the characteristics of the sample. The analytical chapters then follow.

1.2 LSAC overview and study design

LSAC is following two cohorts of children who were selected from across Australia. The B ("baby") cohort was aged 0-1 years at the beginning of the study (born between March 2003 and February 2004); and the K ("kindergarten") cohort was aged 4-5 years at the beginning of the study (born between March 1999 and February 2000).

The first wave of data collection took place in 2004, with subsequent main waves every two years. This report includes data collected from these main waves, up to Wave 6, which was conducted in 2014. In covering the first six waves of the study, this report includes data on children between the ages of 0 and 15 years. Table 1.1 summarises the ages and sample sizes for the two cohorts across these waves of the study. Note that from Wave 3 there is data on children of the same age from both cohorts at different time points. This is a particular feature of LSAC known as an "accelerated cross-sequential" design.

Table 1.1: Age ranges and numbers of children, B and K cohorts, Waves 1-6

	Wave 1 (2004)	Wave 2 (2006)	Wave 3 (2008)	Wave 4 (2010)	Wave 5 (2012)	Wave 6 (2014)
B cohort	0-1 year 5,107	2-3 years 4,606	4-5 years 4,386	6-7 years 4,242	8-9 years 4,085 a	10-11 years 3,764
K cohort	4-5 years 4,983	6-7 years 4,464	8-9 years 4,331	10-11 years 4,169	12-13 years 3,956	14-15 years 3,537

Notes: This table presents the numbers of children who responded at each wave.

1.3 Respondents and collection methods

The use of multiple respondents in LSAC provides a rich picture of children's lives and development in various contexts. Across the first six waves of the study, data were collected from:

• parents of the study child:
  • Parent 1 (P1) - defined as the parent who knows the most about the child (not necessarily a biological parent);¹
  • Parent 2 (P2), if there is one - defined as another person in the household with a parental relationship to the child, or the partner of Parent 1 (not necessarily a biological parent); and
  • a parent living elsewhere (PLE), if there is one - a parent who lives apart from Parent 1 but who has contact with the child (not necessarily a biological parent);
• the study child;
• carers/teachers (depending on the child's age); and
• interviewers.

In earlier waves of the study, the primary respondent was the child's Parent 1. In the majority of cases, this was the child's biological mother, but in a small number of families this was someone else who knew the most about the child. Since Wave 2, the K-cohort children have answered age-appropriate interview questions, and from Wave 4 they have also answered a series of self-complete questions. The B-cohort children answered a short set of interview questions in Wave 4 for the first time. As children grow older, they are progressively becoming the primary respondents of the study.

A variety of data collection methods are used in the study, including:

• conducting face-to-face interviews:
  • on paper; and
  • by computer-assisted interview (CAI);
• filling in self-complete questionnaires:
  • during interview (paper forms, computer-assisted self-interviews (CASI) and audio computer-assisted self-interviews (ACASI);
  • on leave-behind paper forms;
  • on mail-out paper forms; and
  • on Internet-based forms;
• physically measuring the child, including height, weight, girth, body fat and blood pressure;
• directly assessing the child's vocabulary and cognition;
• completing time use diaries;
• conducting computer-assisted telephone interviews (CATI); and
• linking to administrative or outcome data (e.g. Medicare, MySchool).

The interviews and questionnaires include validated scales appropriate to the children's ages.

1.4 Sampling and survey design

The sampling unit for LSAC is the study child. The sampling frame for the study was the Medicare Australia (formerly Health Insurance Commission) enrolments database, which is the most comprehensive database of Australia's population, particularly of young children. In 2004, approximately 18,800 children (aged 0-1 or 4-5 years) were sampled from this database, using a two-stage clustered design. In the first stage, 311 postcodes were randomly selected (very remote postcodes were excluded due to the high cost of collecting data from these areas). In the second stage, children were randomly selected within each postcode, with the two cohorts being sampled from the same postcodes.

A process of stratification was used to ensure that the numbers of children selected were roughly proportionate to the total numbers of children within each state/territory, and within the capital city statistical districts and the rest of each state. The method of postcode selection took into account the number of children in the postcode; hence, all the potential participants in the study Australia-wide had an approximately equal chance of selection (about one in 25). See Soloff, Lawrence, and Johnstone (2005) for more information about the study design.

1.5 Response rates

The 18,800 families selected were then invited to participate in the study. Of these, 54% of families agreed to take part in the study (57% of B-cohort families and 50% of K-cohort families). About 35% of families declined to participate (33% of B-cohort families and 38% of K-cohort families), and 11% of families could not be contacted (e.g., because the address was out-of-date or only a post office box address was provided) (10% of B-cohort families and 12% of K-cohort families).

This resulted in a nationally representative sample of 5,107 0-1 year olds and 4,983 4-5 year olds who were Australian citizens or permanent residents. This Wave 1 sample was then followed up at later waves of the study, with sample numbers and response rates for each of the main waves presented in Table 1.2.

Table 1.2: Response rates, main waves, B and K cohorts, Waves 1-6

	Wave 1	Wave 2	Wave 3	Wave 4	Wave 5	Wave 6
B cohort
umber of responses	5,107	4,606	4,386	4,242	4,077b	3,764
Response rates of Wave 1 (%)	100.0	90.2	85.9	83.0	80.0	73.7
Response rates of available sample (%)a	-	91.2	88.2	86.0	83.5	83.9
K cohort
Number of responses	4,983	4,464	4,332c	4,164c	3,952c	3,537
Response rates of Wave 1 (%)	100.0	89.6	86.9	83.6	79.4	71.0
Response rates of available sample (%)a	-	90.9	89.7	87.2	83.6	80.5
Total
Number of responses	10,090	9,070	8,718	8,406	8,029	7,301
Response rates of Wave 1 (%)	100.0	89.9	86.4	83.3	79.7	72.3
Response rates of available sample (%)a	-	91.1	89.0	86.6	83.5	82.2

Notes: This table refers to the numbers of parents who responded at each wave. Percentages based on weighted data using the Wave 6 data release.^aThe available sample excludes those families who opted out of the study between waves.^b   B cohort: different numbers of parents and their children responded at Wave 5 (there were eight cases where a child interview was completed and the main interview with the parents was not).^cK cohort: different numbers of parents and their children responded at Wave 3 (in one case a parent interview was completed and the interview with the study child was not); Wave 4 (in five cases a child interview was completed and the main interview with the parents was not); and Wave 5 (in four cases a child interview was completed and the main interview with the parents was not).

1.6 Analyses presented in this report

This report includes data from the first six main waves of the study, though given the breadth and depth of topics included in the study, chapters in this report do not necessarily use data from all six waves and/or both cohorts.

Each chapter addresses a series of policy-relevant questions using descriptive statistical analyses. In answering these questions, chapters generally take one or more of the following approaches:

• comparisons between subpopulation groups(see section 1.7 for examples of possible groups) on the various aspects of children's environments and development; and
• examinations of trends across waves as children get older.

Sample weights (for the study children) have been produced for the study dataset in order to reduce the effect of bias in sample selection and participant non-response (Cusack & Defina, 2014; Daraganova & Sipthorp, 2011; Misson & Sipthorp, 2007; Sipthorp & Misson, 2009; Soloff et al., 2005; Soloff, Lawrence, Misson, & Johnstone, 2006). When these weights are used in the analysis, greater weight is given to population groups that are under-represented in the sample, and less weight to groups that are over-represented in the sample. Weighting therefore ensures that the study sample more accurately represents the sampled population.

These sample weights have been used in analyses presented throughout this report. Cross-sectional or longitudinal weights have been used when examining data from more than one wave. Analyses have also been conducted using Stata®svy(survey) commands, which take into account the clusters and strata used in the study design when producing measures of the reliability of estimates. Statistical indicators that are used in this report are given in Table 1.3.

Table 1.3: Statistical indicators in tables and graphs

Indicator	Notes
***	Significance levelp< .001
**	Significance levelp< .01
*	Significance levelp< .05
ns	Not statistically significant
I	Confidence interval

1.7 Commonly used LSAC terms

There are some terms used throughout the analyses of LSAC that are useful to understand:

• Parent 1 is defined as the child's primary caregiver or the parent who knows the child best. The majority of Parent 1 respondents were mothers (i.e., at all waves, more than 95% of Parent 1 respondents have been women and the majority of Parent 2 respondents have been men).
• Parent 1 for each study child was defined by the family at Wave 1. At subsequent waves, the preference, where possible, has been to retain the same person as Parent 1 to maintain the longitudinal consistency of the data. However, if Parent 1 no longer resides with the child or is temporarily away, Parent 2 of the previous wave becomes Parent 1. If both Parent 1 and Parent 2 do not reside with the child or are temporarily away, then a new Parent 1 (the best person to ask about the child's health, development and care) is assigned. Thus, Parent 1 and Parent 2 are sometimes not the same person in each wave, with different parents or guardians potentially occupying different roles at each wave.
• Unless specifically noted, all references to the child's "household" or "family" are to those of Parent 1, and do not include any other household or family the child may have with a parent living elsewhere. Similarly, unless specified in the chapter, any reference to "parents" is to Parent 1 and Parent 2, not to parents living elsewhere. In some chapters, data are reported for mothers and fathers rather than for Parent 1 and Parent 2.

A list of terms relating to LSAC that are often used in this report is presented in Table 1.4.

Table 1.4: Glossary of LSAC terms

Term	Description
B cohort	The younger group ("baby" cohort) of study children, aged: 0-1 years in Wave 1 (2004); 2-3 years in Wave 2 (2006); 4-5 years in Wave 3 (2008); 6-7 years in Wave 4 (2010); 8-9 years in Wave 5 (2012); and 10-11 years in Wave 6 (2014).
K cohort	The older group ("kindergarten" cohort) of study children, aged: 4-5 years in Wave 1 (2004); 6-7 years in Wave 2 (2006); 8-9 years in Wave 3 (2008); 10-11 years in Wave 4 (2010); 12-13 years in Wave 5 (2012); and 14-15 years in Wave 6 (2014).
LSAC	Growing Up in Australia: The Longitudinal Study of Australian Children. A nationally representative longitudinal birth cohort study that commenced in 2004. Data are being collected from study children and their parents, carers and teachers, and through linkage with other national datasets.
Parent 1	The child's Parent 1 (P1) is defined as the child's primary caregiver, or the parent who knows the child best, as determined. In the majority of cases, this is the child's biological mother, but is sometimes the father or another guardian.
Parent 2	The child's Parent 2 (P2) lives in the same household as Parent 1 and is usually the partner of Parent 1. In most cases, this is the child's biological father, but can be the mother, another partner of Parent 1 or another guardian.
Parent living elsewhere (PLE)/non-resident parent	The child's parent who lives in a different household to Parent 1.
Study child (or child)	The sampling unit for LSAC is the study child, so "child" refers to the child selected for inclusion in the study. Data collected and reported relate to this child.
Wave	Periods of data collection: Wave 1 in 2004 (B cohort were 0-1 years, K cohort were 4-5 years); Wave 2 in 2006 (B cohort were 2-3 years, K cohort were 6-7 years); Wave 3 in 2008 (B cohort were 4-5 years, K cohort were 8-9 years); Wave 4 in 2010 (B cohort were 6-7 years, K cohort were 10-11 years); Wave 5 in 2012 (B cohort were 8-9 years, K cohort were 12-13 years); and Wave 6 in 2014 (B cohort were 10-11 years, K cohort were 14-15 years).

1.8 Key variables and subpopulation groups

Each of the chapters of the Annual Statistical Report includes information about the data and the variables used in that chapter. However, there are some variables that are commonly used in LSAC research, in these chapters and elsewhere. They are presented here in Tables 1.5 and 1.6. The percentages shown in these tables are based on weighted data (as described in section 1.6).

Child characteristics

Key child characteristics at the first six waves are summarised in Table 1.5. They are:

Child gender

Parent 1 reported the child's gender at Wave 1.

Child birth order

At each wave, the birth order of the study child was determined based on the number of younger siblings and older siblings in the household. The birth order of the study child was classified as the oldest child, middle child or twins, youngest child or only child in the household.

Table 1.5: Child characteristics, B and K cohorts, Waves 1-6

Subpopulation categories	B cohort						K cohort
	Wave 1 0-1 years (%)	Wave 2 2-3 years (%)	Wave 3 4-5 years (%)	Wave 4 6-7 years (%)	Wave 5 8-9 years (%)	Wave 6 10-11 years (%)	Wave 1 4-5 years (%)	Wave 2 6-7 years (%)	Wave 3 8-9 years (%)	Wave 4 10-11 years (%)	Wave 5 12-13 years (%)	Wave 6 14-15 years (%)
Child gendera
Boys	51.1	51.1	51.1	51.1	51.2	51.3	51.2	51.3	51.3	51.2	51.8	51.4
Girls	48.9	48.9	48.9	48.9	48.8	48.7	48.8	48.7	48.7	48.8	48.2	48.6
n	5,107	4,606	4,386	4,242	4,085	3,764	4,983	4,464	4,331	4,169	3,956	3,537
Child birth order
Oldest child	0.2	19.6	29.1	31.4	33.2	34.1	28.8	31.4	32.9	34.6	36.3	38.1
Middle child/Twin	1.8	13.1	19.6	21.7	22.3	22.0	18.4	20.5	21.4	21.5	20.5	18.8
Youngest child	58.9	47.4	39.9	37.4	35.6	34.1	41.4	38.5	37.1	35.3	33.7	31.1
Only child	39.1	19.9	11.4	9.5	9.0	9.8	11.5	9.6	8.6	8.6	9.5	12.0
n	5,107	4,606	4,386	4,242	4,077	3,759	4,983	4,464	4,331	4,164	3,951	3,526
Main language spoken at home by childa
English	87.2	87.9	87.0	86.8	89.2	87.6	86.0	85.2	86.1	85.9	88.7	86.8
Not English	12.8	12.1	13.0	13.2	10.8	12.4	14.0	14.8	13.9	14.1	11.3	13.2
n	5,104	4,603	4,384	4,239	4,084	3,763	4,983	4,464	4,331	4,164	3,956	3,537
Child Indigenous statusa
Indigenous	4.9	5.1	4.9	5.2	4.4	3.7	3.9	3.7	3.7	3.8	2.9	2.6
Non-Indigenous	95.1	94.9	95.1	94.8	95.6	96.3	96.1	96.3	96.3	96.2	97.1	97.4
n	5,107	4,606	4,386	4,242	4,085	3,764	4,981	4,462	4,329	4,167	3,954	3,535
Child has a disability or medical conditionb
Yes	-	5.9	8.6	5.4	4.1	5.1	-	11.1	7.7	6.2	4.7	4.3
No	-	94.1	91.4	94.6	95.9	94.9	-	88.9	92.3	93.8	95.3	95.7
n	-	4,606	4,386	4,242	4,047	3,695	-	4,464	4,331	4,164	3,913	3,454
Child weight statusc
Underweight	-	5.3	6.5	5.4	5.1	6.9	5.2	5.1	5.5	5.9	6.7	6.5
Normal weight	-	71.3	69.7	73.8	71.1	67.3	74.2	75.2	69.5	65.6	65.7	64.9
Overweight or obese	-	23.4	23.8	20.8	23.9	25.7	20.6	19.7	25.0	28.5	27.5	28.5
n	-	4,522	4,324	4,181	3,998	3,574	4,934	4,423	4,289	4,018	3,803	3,276

Notes: Percentages based on weighted data using the Wave 6 data release.^a Recorded at Wave 1.^bQuestions about whether the study child had a disability or medical condition were asked differently in Wave 1 so these data are not included here. Further, differences in the prompt cards for these questions in Waves 3 and 4 mean that the disability data should not be compared across waves.^c Weight status is based on body mass index. It was not calculated at Wave 1 for the B cohort.

Main language spoken at home by child

At Wave 1, Parent 1 respondents were asked whether they mainly spoke English or a language other than English at home. Languages were classified according to the Australian Standard Classification of Languages (Australian Bureau of Statistics [ABS], 2005), and these were summarised into English or non-English languages.

Child has a disability or medical condition

At each of Waves 2 to 5, Parent 1 respondents were asked whether each household member had a medical condition or disability that had lasted six months or more, while being shown a prompt card with a list of conditions such as sight problems; hearing problems; blackouts, fits or loss of consciousness; difficulty learning or understanding things; and difficulty gripping things.

Child weight status

At each wave (except Wave 1 for the B cohort), interviewers measured the children's weight and height, and these measurements were used to calculate children's body mass index (BMI). The children were then classified as overweight or obese (Cole, Bellizzi, Flegal, & Dietz, 2000), underweight (Cole, Flegal, Nicholls, & Jackson, 2007) or of normal weight. Children in the B cohort at Wave 1 were not measured because of the technical difficulties of measuring infants' height and weight. Instead, study child's birth weight and length were recorded.

Child Indigenous status

Parent 1 respondents identified at Wave 1 whether the study child was of Aboriginal and/or Torres Strait Islander background. These results were summarised into a measure of whether the child was Indigenous or non-Indigenous.

Parent and family characteristics

The parent and family characteristics at the first six waves are summarised in Table 1.6.

Household structure

The household structure was classified using the demographic information of Parent 1's and Parent 2's gender, relationship to the study child and presence at each wave. The "two-biological parent" households refer to children's primary households that include two biological parents (a mother and a father). The "single-biological parent" households refer to children's primary households in which the study child lived with one biological parent only (Parent 2 was absent at the wave). Most of the single parents were single mothers (97%). The "one biological and step-parent" households include households where the study child lived with a biological parent and a step, adoptive or foster parent - the vast majority of these children lived in households with a biological mother and a step-father.

The "two non-biological parents" and "one non-biological parent" households include those headed by adoptive parents, grandparents or other relatives, and foster parents. The "biological and other parents" household refer to children's primary household where there was a biological parent and an unrelated adult or a relative to the study child (e.g., grandparent). This "unrelated adult" was usually the cohabiting (e.g., legal spouse, rather than married) partner to the biological parents.

Family socio-economic position

The measure of family socio-economic position (SEP), developed by Blakemore, Strazdins, and Gibbings (2009), uses information about combined annual family income, educational attainment of parents and parents' occupational status to summarise the social and economic resources available to families. The standardised SEP scores have been divided into quartiles and summarised into the lowest 25%, the middle 50% and the highest 25%. From Wave 2 onwards, the SEP variable is calculated based on the ANZSCO (Australian and New Zealand Standard Classification of Occupations) occupation standard, which was introduced in 2006. SEP measures based on the previous occupation standard (ASCO) are available in the dataset for Waves 1 to 4.

Table 1.6: Parent and family characteristics, B and K cohorts, Waves 1-6

Subpopulation categories	B cohort						K cohort
	Wave 1 0-1 years (%)	Wave 2 2-3 years (%)	Wave 3 4-5 years (%)	Wave 4 6-7 years (%)	Wave 5 8-9 years (%)	Wave 6 10-11 years (%)	Wave 1 4-5 years (%)	Wave 2 6-7 years (%)	Wave 3 8-9 years (%)	Wave 4 10-11 years (%)	Wave 5 12-13 years (%)	Wave 6 14-15 years (%)
Household structure
Two biological parents	88.9	85.7	82.3	78.6	76.5	73.8	81.7	79.0	75.2	72.3	72.0	68.4
Single biological parent	10.4	13.1	14.0	15.8	15.9	17.2	14.7	16.7	16.7	18.3	18.0	19.8
Biological parent and step-parent	0.2	0.5	2.0	3.3	4.6	5.1	2.3	2.9	4.4	5.2	6.6	7.6
Other	0.5	0.7	1.7	2.4	3.0	3.8	1.2	1.5	3.8	4.4	3.4	4.1
n	5,107	4,606	4,386	4,238	4,077	3,759	4,983	4,464	4,331	4,150	3,952	3,526
Family socio-economic positiona
Lowest 25%	28.6	30.9	31.3	32.9	30.7	31.4	28.6	30.3	31.5	32.1	30.0	31.3
Middle 50%	48.9	48.0	47.8	46.8	47.8	48.1	50.0	48.8	48.8	48.4	49.3	38.6
Highest 25%	22.5	21.2	20.9	20.3	21.5	20.5	21.4	20.9	19.7	19.6	20.7	20.1
n	5,092	4,585	4,367	4,215	4,036	3,707	4,965	4,458	4,327	4,124	3,907	3,439
Number of siblings in the household
None	39.1	19.9	11.4	9.5	9.0	9.8	11.5	9.6	8.6	8.6	9.5	12.0
One	36.4	47.3	46.3	43.6	42.5	42.5	47.5	43.9	42.5	42.5	43.4	44.3
Two or more	24.5	32.8	42.3	46.9	48.5	47.7	41.0	46.5	48.9	48.9	47.1	43.7
n	5,107	4,606	4,386	4,242	4,077	3,759	4,983	4,464	4,331	4,164	3,951	3,526
Main language spoken at home by Parent 1
English	83.1	83.7	83.1	82.8	85.6	83.7	82.5	81.6	82.7	82.6	84.8	83.6
Not English	16.9	16.3	16.9	17.2	14.4	16.3	17.5	18.4	17.3	17.4	15.2	16.4
n	5,107	4,606	4,386	4,238	4,077	3,759	4,983	4,464	4,328	4,146	3,952	3,526
Parent 1's country of birth
Overseas	23.2	22.7	23.2	23.4	22.0	22.3	25.8	26.3	25.9	25.8	24.6	25.1
Australia	76.8	77.3	76.8	76.6	78.0	77.7	74.2	73.5	74.1	74.2	75.4	74.9
n	5,107	4,606	4,386	4,242	4,077	3,759	4,982	4,463	4,327	4,159	3,952	3,526
Parent 1's education level
University degree or higher	29.1	28.3	29.6	30.0	33.4	32.2	24.1	24.4	25.1	25.8	28.7	28.1
Less than university degree	70.9	71.7	70.4	70.0	66.6	67.8	75.9	75.6	74.9	74.2	71.3	71.9
n	5,107	4,606	4,386	4,242	4,085	3,764	4,983	4,464	4,331	4,164	3,956	3,537
Both parents' education level
At least one parent has a university degree (or higher)	37.5	36.9	38.4	38.9	42.4	41.8	33.9	34.3	35.0	35.3	38.8	38.3
Neither parent has a university degree	62.5	63.1	61.6	61.1	57.6	58.2	66.1	65.7	65.0	64.7	61.2	61.7
n	5,104	4,604	4,385	4,240	4,075	3,756	4,979	4,463	4,329	4,163	3,948	3,522
Parent 1's employment
Employed	47.6	55.5	61.0	64.3	71.1	75.0	55.3	63.9	70.9	72.3	76.9	78.9
Unemployed	3.4	3.3	2.3	3.2	3.1	3.2	4.3	3.4	2.9	2.8	2.9	2.8
Not in the labour force	49.0	41.3	36.7	32.6	25.8	21.8	40.4	32.7	26.1	25.0	20.2	18.3
n	5,096	4,606	4,383	4,233	4,070	3,754	4,972	4,463	4,330	4,162	3,948	3,468
Jobless family
No	87.0	87.4	89.0	89.1	90.6	91.0	86.7	89.1	91.1	89.9	91.4	91.7
Yes	13.0	12.6	11.0	10.9	9.5	9.0	13.2	10.9	9.0	10.1	8.6	8.3
n	5,104	4,606	4,383	4,240	4,077	3,754	4,977	4,463	4,330	4,166	3,950	3,468
Region of residence
Metropolitan	66.5	62.6	64.9	63.6	62.8	62.0	63.7	65.9	62.9	62.4	62.0	61.5
Non-metropolitan	33.5	37.4	35.1	36.4	37.2	38.0	36.3	34.1	37.1	37.6	38.0	38.5
n	5,107	4,606	4,378	4,231	4,079	3,756	4,983	4,464	4,324	4,163	3,952	3,527
Neighbourhood disadvantage
Disadvantaged	27.5	31.1	30.8	30.3	28.7	33.1	28.2	31.0	30.8	30.2	30.5	29.9
Non-disadvantaged	72.5	68.9	69.2	69.7	71.3	66.9	71.8	69.0	69.2	69.8	69.5	70.1
n	5,107	4,606	4,386	4,240	4,077	3,764	4,983	4,464	4,331	4,168	3,951	3,536

Notes: Percentages based on weighted data.

Number of siblings in the household

At each wave, Parent 1 provides details about all household members, including the study child's siblings. Siblings include biological, adopted, foster, step- and half-siblings. Children may also have siblings who do not live in their household but these siblings are not included here.

Main language spoken at home by Parent 1

The language spoken by Parent 1 is classified using the same approach described for the study children above.

Parent 1's country of birth

Parent 1 is grouped into "Australian born" or "born overseas" based on their country of birth provided at Wave 1.

Parents' education level

At each wave, Parent 1 respondents are asked about the highest qualification held by each of the parents. This information is used to categorise parents into those who have a university degree (or higher) and those who don't. Comparisons are made for Parent 1 respondents only, and for both parents together (families in which at least one parent has a university degree, versus families in which neither parent has a university degree).

Parents' employment status

At each wave, Parent 1 reported their employment status as "employed (includes full-time and part-time employment)", "unemployed" or "not in the labour force". Jobless family was derived using Parent 1 and Parent 2's employment status. Jobless family refers to two-parent families where both parents were unemployed or not in the labour force, and single-parent families where Parent 1 was unemployed or not in the labour force.

Region of residence

Families' postcodes are used to link to ABS Census data, which identifies whether they live in a metropolitan area (capital city statistical divisions) or non-metropolitan area (the rest of the state outside the capital city statistical divisions).

Neighbourhood disadvantage

Neighbourhood disadvantage was measured using the Socio-Economic Indexes for Areas (SEIFA) - Disadvantage. Those families living in areas in the lowest 25% SEIFA index of disadvantage are considered to be living in an area of socio-economic disadvantage.

The LSAC data documentation provides more information about these items and the study itself.

1.9 References

Australian Bureau of Statistics. (2005).Australian Standard Classification of Languages (ASCL). Canberra: ABS.

Australian Institute of Family Studies. (2011).The Longitudinal Study of Australian Children annual statistical report 2010. Melbourne: AIFS.

Blakemore, T., Strazdins, L., & Gibbings, J. (2009). Measuring family socioeconomic position. Australian Social Policy,8, 121-168.

Cole, T. J., Bellizzi, M. C., Flegal, K. M., & Dietz, W. H. (2000). Establishing a standard definition for child overweight and obesity worldwide: International survey. British Medical Journal,320, 1240-1243.

Cole, T. J., Flegal, K. M., Nicholls, D., & Jackson, A. A. (2007). Body mass index cut offs to define thinness in children and adolescents: International survey. British Medical Journal,335(7612), 194.

Cusack, B., & Defina, R. (2014).Wave 5 weighting & non response (Technical Paper No. 10). Melbourne: Australian Institute of Family Studies.

Daraganova, G., & Sipthorp, M. (2011).Wave 4 weights(Technical Paper No. 9). Melbourne: Australian Institute of Family Studies.

Misson, S., & Sipthorp, M. (2007).Wave 2 weighting and non-response(Technical Paper No. 5). Melbourne: Australian Institute of Family Studies.

Sipthorp, M., & Misson, S. (2009).Wave 3 weighting and non-response(Technical Paper No. 6). Melbourne: Australian Institute of Family Studies.

Soloff, C., Lawrence, D., & Johnstone, R. (2005).LSAC sample design(Technical Paper No. 1). Melbourne: Australian Institute of Family Studies.

Soloff, C., Lawrence, D., Misson, S., & Johnstone, R. (2006).Wave 1 weighting and non-response. Melbourne: Australian Institute of Family Studies.